It's a matter of breath control. You need to be able to generate a scream or the sound of one in a controlled way not using all of the force of your breath. you need to do this because you need to be able to carry the sound for more than a few seconds, and that requires saving air and controlling it. Use the vocal amplifier to generate the volume and concentrate on making the vocal without destroying your vocal cords. full screaming will damage your cords. so use the mic and the amp as part of your instrument and you will find the mic and amp will find bits of sounds that you did not know were there. Find them by recording yourself and listening to experimentations with actual words and ways to vocalize them. Work on the sounds you want so you can repeat them and call on them when you want them. Then its a matter of changing pitches to give the vocal some range of keys, maybe two octaves is the best you will get with this kind of vocal. more than that and you will find the strain will limit you bouth in endurance and consistency. Try "screaming" in a normal conversation volume, its not easy to make it sound real. But then the amp and mic are your partners and will help you there. its gonna take a lot of work if you are serious to develop the stamina and breath control to get what you want, Good Luck ! Can or Cant do ? you will not know unless you try. maybe you can scream but can you pitch it to a note ? thats the problem isnt it. you have to work to get there and there are no shortcuts. go to work !!